Scene object geometry, i.e. the geometric distribution and relationship, for natural scene photography is valuable information that can be used to process digital images produced by digital cameras. In particular, knowing the separation distance between the camera and scene object along the line-of-sight from camera to object can be used to calculate the separation distance from object to object within the scene.
There are examples of semi-manual and automatic prior art in this field. In “Multiple View Geometry in Computer Vision Second Edition,” Cambridge University Press, March 2004, R. Hartley, et al. disclose several methods for determining 3D information (and hence distance information) from a 2D image. One method is accomplished by taking several captures of a scene from different viewing angles. Through user intervention of assigning geometric structures to certain features in the image, the Euclidean 3D geometry of the scene can be derived. According to Hartley, by using techniques of projective geometry, it is possible in many instances to reconstruct scenes from a single image. This cannot be done without some assumptions being made about the imaged scene (e.g. the physical distance between at least two imaged points should be known). It is not yet possible for such techniques to be fully automatic. However, projective geometric knowledge can be built into a system that permits user-guided single-view reconstruction of a scene. A further method described by Hartley requires that all points of the scene are visible in all images.
A significant problem with existing distance measurement methods is that they require considerable processing to determine distance. These methods often require user intervention as well as specific setups for the capture of the image. In addition, these methods are often very computationally intensive and complex.